The aims of the study are aim to evaluate whether a treatment based on the EMDR protocol can resolve PTSD or reduce PTS symptoms, also improving the PTS-associated symptoms, such as anxiety and depression. Primary objective : to evaluate the efficacy of the treatment with EMDR on the PTSD in MS. Secondary objectives : To evaluate whether after treatment with EMDR there is an improvement in PTS-associated symptoms of anxiety and depression and an improvement in quality of life.